1. Field of the Invention
The present invention relates to a pressure apparatus. In particular, the invention relates to a pressure apparatus incorporated in a chip mounter designed to mount an electronic component chip on a printed circuit board.
2. Description of the Prior Art
As disclosed in Japanese Patent Application Publication No. 2003-229442, for example, a chip mounter is well known. A contact member such as a head is opposed to the upper surface of a work stage in the chip mounter. The chip mounter includes a movable member designed to move in the direction perpendicular to the upper surface of the work stage. A guide is disposed to support the movement of the movable member. A support shaft is attached to the lower end of the movable member. A head is fixed to the lower end of the support shaft. A load cell is interposed between the support shaft and the movable member. When the head is urged against a substrate on the work stage, the load cell is employed to measure the magnitude of the pressure force.
The head of the chip mouter often suffers from swinging movement around the load cell based on the imbalance of the mass. This swinging movement of the head induces the resonance at a lower frequency of a servo control bandwidth. The resonance at the lower frequency hinders accomplishment of the positioning of the head at a higher speed. The tact time cannot be shortened in the chip mounter.